Investigation on the fracture toughness of concrete-rock interface damaged by high-pressure water environment

This paper is concerned with the effect of a high-pressure water environment on the fracture property of the concrete-rock interface. Three mechanically-grooved rock interfaces were per -formed, and a high-pressure water loading system was used to apply stable water pressure (0, 1, 2, 4 MPa) to the concrete-rock composite specimens for 48 h. Finally, a three-point bending (TPB) test on the concrete-rock composite specimens was carried out in a natural environment. The results showed that the action of high-pressure water resulted in a reduction in the deformation capacity of TPB specimens, with the interface being more prone to cracking and the maximum load decreased. The energy release rate could be reduced by up to 50%. The damage to the interface bond performance and the elastic modulus of concrete and rock can add a mechanistic explanation to the property deterioration of TPB specimens after high-pressure water action. The smaller the rock roughness, the more pronounced the effect of high-pressure water damage on the fracture property of the concrete-rock interface. Empirical formulas have been proposed for the initial cracking load and maximum load of a standard concrete-rock TPB beam. Moreover, a model for the fracture initiation toughness of the concrete-rock interface has been modified to consider the effects of high-pressure water damage and rock roughness.